I need to know about the largest auto dealerships in the USA. I mean
square footage of the building(s), not acreage of the land. Ideal
would be top five with name of dealership, location (city) and square
footage.  At least, the name, city and square footage of the largest
auto dealership in the USA.

Greetings Gogo3,
I hope you will approve of my posting my answer here in the form of an
organized list of the dealerships. I did my own searching as well as
used the Capital Automotive REIT website. I organized the results from
top to bottom, largest first:

Lusardi Construction Company - News - Newsletter
http://www.lusardi.com/news/chauncey.htm
Chauncey Ranch Auto Mall - 435,000 to 500,000 sq. ft.
North Scottsdale Road Arizona

HoustonChronicle.com - Development: Southwest area crossroads of
ethnic trade
http://www.chron.com/cs/CDA/ssistory.mpl/special/chron10003/1926573
- Gillman Dealership , 250,000 sq. ft.
10595 West Sam Houston Parkway South
Houston, Texas 77099
Telephone: (713) 776-7005
Fax: (713) 776-4849
Toll Free: 1-800-933-7809
http://www.gillmanauto.com/main.html

Capital Automotive REIT - Real Estate Portfolio as of March 31, 2003
http://www.capitalautomotive.com/PDFs/Q1-2003/Real%20Estate%20Portfolio%2003-31-03.pdf
Found in: http://www.capitalautomotive.com/portfolio/properties.htm

Park Place Motorcars - 238,623 sq. ft.
Dallas, Texas

Global Imports - 157,680 sq. ft.
Atlanta, Georgia 

Denver Toyota - 148,461 sq. ft.
Denver, Colorado

Massey Cadillac Saab - 145,749 sq. ft.
Orlando, Florida

Lone Star Chevrolet - 130,686 sq. ft.
Houston, Texas

Town & Country Ford - 124,695 sq. ft.
Charlotte, North Carolina

I doubt Armory Garage in Albany will pass since its floor area will
not reach any of the areas above, if I used the 550 car capacity (400
+ 150) mentioned. I gave each car 120 square feet, and it led to only
66,000 feet. There’s not even an acre figure given.

Google Search Terms used:
square feet auto dealership largest
square feet auto dealership biggest

I hope this has been a helpful answer. If you have any problem with
it, do please post a Request for Clarification and I shall respond.
Thank you.

this might be helpful:
http://www.capitalautomotive.com/portfolio/portfolio.htm
 click on portfolio listing on the left.

this company, Capital Automotive (CARS), owns some of the largest
dealerships in the country.

Here's the Largest Dealer Showroom:

Armory Garage-Albany, NY 

We offer you the convenience of shopping, for your new car inside the
world's largest auto showroom as recognized by Ripley's Believe It or
Not, with more than 150 vehicles on display inside and more than 400
outside at all times.

We uaually have over 500 new and used vehicles on our lot. Not the
bigest building by far, but respectable by Oklahoma standards. Check
out our site www.MarcHeitzChevy.com